| Year | Value | | 2022 | 18,934 | | 2021 | 19,362 | | 2020 | 20,050 | | 2019 | 20,833 | | 2018 | 21,663 | | 2017 | 22,537 | | 2016 | 23,277 | | 2015 | 23,779 | | 2014 | 24,051 | | 2013 | 24,123 | | 2012 | 24,163 | | 2011 | 24,310 | | 2010 | 24,326 | | 2009 | 23,936 | | 2008 | 22,911 | | 2007 | 21,304 | | 2006 | 19,515 | | 2005 | 17,770 | | 2004 | 16,339 | | 2003 | 15,257 | | 2002 | 14,323 | | 2001 | 13,463 | | 2000 | 12,503 | | 1999 | 11,231 | | 1998 | 9,790 | | 1997 | 8,440 | | 1996 | 7,298 | | 1995 | 6,399 | | 1994 | 5,802 | | 1993 | 5,527 | | 1992 | 5,470 | | 1991 | 5,413 | | 1990 | 5,288 | | 1989 | 5,169 | | 1988 | 5,046 | | 1987 | 4,957 | | 1986 | 4,942 | | 1985 | 4,973 | | 1984 | 5,040 | | 1983 | 5,143 | | 1982 | 5,235 | | 1981 | 5,279 | | 1980 | 5,295 | | 1979 | 5,284 | | 1978 | 5,236 | | 1977 | 5,178 | | 1976 | 5,128 | | 1975 | 5,091 | | 1974 | 5,044 | | 1973 | 4,966 | | 1972 | 4,851 | | 1971 | 4,715 | | 1970 | 4,599 | | 1969 | 4,524 | | 1968 | 4,457 | | 1967 | 4,402 | | 1966 | 4,375 | | 1965 | 4,344 | | 1964 | 4,242 | | 1963 | 4,117 | | 1962 | 3,998 | | 1961 | 3,834 | | 1960 | 3,778 |
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